From fb3d80e390b8ed3111a4658755b035f5e20eb5e0 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Tue, 24 Dec 2024 00:41:27 +1100
Subject: [PATCH] Fixed connecting discontiguous corners

---
 .../imagedraw/discontiguous_corners_polygon.png | Bin 486 -> 533 bytes
 Tests/test_imagedraw.py                         |   3 +++
 src/libImaging/Draw.c                           |   9 ++++-----
 3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/Tests/images/imagedraw/discontiguous_corners_polygon.png b/Tests/images/imagedraw/discontiguous_corners_polygon.png
index 509c42b26e0cbc5e01853915b083d367c1587579..1b58889c8f3ae45243a7509c907f1928534bcbde 100644
GIT binary patch
delta 507
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delta 460
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C9QgkL

diff --git a/Tests/test_imagedraw.py b/Tests/test_imagedraw.py
index ed50dfbed..5fc1c2766 100644
--- a/Tests/test_imagedraw.py
+++ b/Tests/test_imagedraw.py
@@ -1674,6 +1674,9 @@ def test_continuous_horizontal_edges_polygon() -> None:
 def test_discontiguous_corners_polygon() -> None:
     img, draw = create_base_image_draw((84, 68))
     draw.polygon(((1, 21), (34, 4), (71, 1), (38, 18)), BLACK)
+    draw.polygon(
+        ((82, 29), (82, 26), (82, 24), (67, 22), (52, 29), (52, 15), (67, 22)), BLACK
+    )
     draw.polygon(((71, 44), (38, 27), (1, 24)), BLACK)
     draw.polygon(
         ((38, 66), (5, 49), (77, 49), (47, 66), (82, 63), (82, 47), (1, 47), (1, 63)),
diff --git a/src/libImaging/Draw.c b/src/libImaging/Draw.c
index f1c8ffcff..ea6f8805e 100644
--- a/src/libImaging/Draw.c
+++ b/src/libImaging/Draw.c
@@ -501,7 +501,8 @@ polygon_generic(
                     // Needed to draw consistent polygons
                     xx[j] = xx[j - 1];
                     j++;
-                } else if (current->dx != 0 && roundf(xx[j - 1]) == xx[j - 1]) {
+                } else if (current->dx != 0 && j % 2 == 1 &&
+                           roundf(xx[j - 1]) == xx[j - 1]) {
                     // Connect discontiguous corners
                     for (k = 0; k < i; k++) {
                         Edge *other_edge = edge_table[k];
@@ -510,10 +511,8 @@ polygon_generic(
                             continue;
                         }
                         // Check if the two edges join to make a corner
-                        if (((ymin == current->ymin && ymin == other_edge->ymin) ||
-                             (ymin == current->ymax && ymin == other_edge->ymax)) &&
-                            xx[j - 1] == (ymin - other_edge->y0) * other_edge->dx +
-                                             other_edge->x0) {
+                        if (xx[j - 1] ==
+                            (ymin - other_edge->y0) * other_edge->dx + other_edge->x0) {
                             // Determine points from the edges on the next row
                             // Or if this is the last row, check the previous row
                             int offset = ymin == ymax ? -1 : 1;